Repair fitting for NOx and particulate matter sensors

ABSTRACT

The present invention is an apparatus and method which allows for repair cost reduction in the event an exhaust system becomes damaged during replacement of a NOx or particulate matter sensor. Replacement of only the sensor mount, rather replacement of an entire emissions after-treatment component can return a unit to service with a fraction of the downtime and expense of traditional system replacement. This is accomplished through a developed removal technique for the damaged integral mounting, in conjunction with the installation of a service replacement fitting which has now been developed to embody a new form as a weldable replacement part. This invention allows for the benefits of cost savings and reduced repair downtime, as well as a reduced consumption of rare earth metals used in the construction of emissions after-treatment devices.

CROSS REFERENCE TO RELATED APPLICATIONS

Not applicable to this application

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable to this application

REFERENCES CITED

U.S. Pat. No. 8,459,004 Chang. U.S. Pat. No. 8,728,422 Audouin, U.S. Pat. No. 3,841,842 Wiley, U.S. Pat. No. 5,298,046 Peisert, U.S. Pat. No. 6,216,458 Alger

US PATENT APPLICATIONS

20120269705 Jensen

2 Claims, 1 Image sheet

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a service method and replacement weld fitting for Diesel NOx and particulate matter sensors.

2. Description of the Related Art

Whereas the combustion of hydrocarbon fuels has been, and continues to cause negative environmental consequences, federal emissions standards have become increasingly more stringent in an effort to reduce this impact. To meet these requirements, industrial and automotive powertrain management systems have evolved to become increasingly more complex utilizing multiple on-board computers. These computers process and share data from a plurality of sensors in order to command the most efficient fueling and engine operating strategies possible. This is true both of gasoline, and Diesel powered engines.

As is often the circumstance, components sometimes require replacement. For the purpose of this invention, this is especially true of the Oxides of Nitrogen (NOx hereinafter) and Particulate Matter sensors found most frequently in, but not limited to modern Diesel exhaust systems. Virtually every component in the exhaust system on a 2008 model and newer Diesel engine is actually an emissions control device. Modern Diesel engines use a number of after-treatment systems to clean the exhaust gas before it leaves the tailpipe. This includes; catalytic converters (U.S. Pat. No. 3,841,842) which reduce hydrocarbon emissions, particulate filters (U.S. Pat. No. 5,298,046) which collect soot particles until a regeneration or self-cleaning event occurs which converts the soot emissions to ash. Also, there are selective catalyst reduction systems (U.S. Pat. No. 8,728,422 & US 20120269705) which inject a fluid in to the exhaust to react chemically, thereby reducing emissions of NOx (oxides of nitrogen). Exhaust gas recirculation systems (U.S. Pat. No. 6,216,458) also reduce NOx emissions through the lowering of combustion temperatures by reducing the oxygen content of the air charge under certain conditions. NOx and particulate matter sensors are used by the powertrain management computers to monitor the operation of the aforementioned after-treatment systems. Industry experience has shown these sensors occasionally require replacement.

NOx and particulate matter sensors are installed into integral threaded mountings FIG. 3 at various points along the exhaust system. This allows for exhaust samples at those points to be monitored by the powertrain management computers in order to control and monitor the operation of the exhaust emissions after-treatment systems. In most cases, when such sensors require replacement, it is a simple matter of unscrewing the old sensor, and screwing in the new sensor. Occasionally however, their threads become seized and are damaged during replacement. This is unfortunate, because the mounting in to which they thread—is an integral part of what is usually a highly expensive emissions after-treatment component. This means damaged threads typically renders that entire after-treatment component defective and in need of replacement.

SUMMARY OF THE INVENTION

This invention is a lower cost repair solution, in the form of a stand-alone embodiment weldable service replacement sensor fitting FIG. 2. This invention provides a means to resolve the problem of thread damaged integral mountings for original equipment NOx or particulate matter sensors of specific types. This standalone embodiment service replacement fitting allows for the replacement of just the original integral sensor mounting instead of needing to replace the entire after-treatment component.

To be clear, no claim is being made on sensor fittings generally, as replacement non counterbored fittings for most exhaust oxygen sensors are readily available from several suppliers, and have been for years. One example of many is U.S. Pat. No. 8,459,004 by Chang. So too, have various non counterbored fittings been available for aftermarket style Exhaust temperature sensors—often used for customer installed pyrometer gauges and performance devices. Nor is this a claim on the original counterbored mountings which come equipped on these systems from the factory and are an integral part of their respective exhaust after-treatment component. What is being claimed is an improvement to the originally equipped integral sensor mounting to allow for a lower cost repair solution should one become damaged. To be specific, the development of service replacement counterbored weld fitting as a stand-alone repair embodiment for original equipment NOx and particulate matter sensors FIG. 1. This invention allows for an exhaust after-treatment component with a damaged integral sensor mounting to be repaired instead of having to discard and replace the entire after-treatment component.

BRIEF DESCRIPTION OF THE IMAGES

FIG. 1 depicts a detailed cross sectional view of the standalone embodiment replacement weld fitting. The overall shape, thread pitches 2, measurement range specifications, and chamfer positions 1 are shown. There is also a side and top view of the replacement counterbored weld fitting FIG. 2 AND FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The standalone embodiment service replacement sensor weld fitting is comprised of a machined ferrous bar in a diameter of approximately 1.25 inches. It is approximately 0.5 inches in total height; though the external specifications are less important and could vary. It is the internal specifications that enable it to function, by allowing it to receive and seal against specific types of NOx and particulate matter sensors. Unlike the replacement fittings currently available for oxygen sensors, these are not machined to their threading diameter all the way through, rather, they are only machined to their threading diameter partially FIG. 1. A smaller hole is machined through the remainder of the material 3 to allow for a counterbored sealing surface or seat 4. The smaller hole at the bottom of the fitting is large enough to allow for the sensing probe to protrude through, but not the sensor's seat FIG. 1. This allows for a sealing off of exhaust gasses, as well as a tightening of the sensor's nut once the sensor's compression seat bottoms against the corresponding counterbore within the fitting FIG. 1. The invention of these service replacement fittings allows for a damaged integral sensor mounting to be severed from its respective after-treatment component by means of standard metalworking practices. Whereupon one of these service replacement fittings can be affixed in its place by means of standard welding or brazing practices. Once a service replacement fitting has been affixed, a new sensor may then be installed. This restores the unit to operation for a fraction of the cost of replacing the entire after-treatment component—which had been the only repair option heretofore. 

1. A component to repair an exhaust system construct inside of which an oxides of nitrogen (NOx hereinafter) or particulate matter sensor's threads have been damaged, comprising: a replacement embodiment counterbored weld fitting into which a NOx or particulate sensor is installed, said fitting further comprising; a) a weldable ferrous machined part with internal ISO threads to receive the replacement NOx or particulate matter sensor of the type which comprises an externally threaded sensor nut, compression seat, and a sensing probe that would protrude through the aforementioned fitting once installed, b) said internal threads leading to or near a counterbored surface against which sealing will occur upon tightening of the aforementioned sensor's nut, c) a smaller hole penetrating the center of the internal structure to create the counterbore through which a sensor's probe will protrude to reach the internal space of its respective emissions after-treatment construct or conduit through which exhaust is transferred from a combustion engine.
 2. A method of repair utilizing the replacement weld fitting of claim 1, comprising: a) heating the damaged integral mounting with an oxygen acetylene torch to the melting point of its base material, b) simultaneously applying torque by means of a pipe wrench or other suitable tool, c) twisting said tool until the integral mounting structure is cleanly severed from the exhaust system construct, d) affixing the replacement fitting of claim 1 to said exhaust system construct by means of appropriate welding or brazing practices, whereupon a replacement NOx or particulate matter sensor will be installed in said replacement fitting. 